An operator drilling in the South Central Oklahoma Oil Province (SCOOP) set casing higher than the planned depth (11,433-ft. in the 121⁄4-in. hole section), exposing the fragile Red Fork formation. The operator was unable to achieve the desired formation integrity test (FIT) to 14.0 lb/gal equivalent mud weight (EMW) to continue drilling the interval. The formation began to break down at approximately 2070 psi and the FIT was deemed unsuccessful.
A 40 bbl pill consisting of 30 lb/bbl STAR SHIELD 3000 was spotted around the casing shoe. STAR SHIELD 3000 seals fractures up to 3,000 microns and creates a fast and effective barrier, whether fractures are natural or induced. The FIT was performed using a 10.0 lb/gal water-based mud (WBM) to a max pressure of 2557 psi, which bled back to 2493 psi (13.9 ppg EMW) over 10 minutes. The pressure was then released and the 10.0lb/gal WBM was displaced with a 13.6 oil-based mud (OBM). Full returns were lost.
The bit was pulled inside the casing and the operator squeezed a 40 bbl pill (30 lb/bbl STAR SHIELD 3000 and 20 lb/bbl STAR SHIELD500) down the 27-ft. of open hole below the casing shoe. While beginning to pump the pill into the drill string, the hole packed off and the pipe became stuck. After freeing the drill string, the remainder of the pill was pumped. After pumping 349 strokes (25 bbls) circulation was re-established with 100% returns. Circulation resumed with 13.6 lb/gal OBM.
The mud weight was reduced to 13.1 lb/gal reducing the equivalent circulating density (ECD) on the formation and the operator drilled to total depth (TD). The operator was extremely satisfied to regain full returns and to achieve a successful FIT.